1. Technical Field
This invention relates to mobile telecommunications and, more particularly, to defining how to handle an out-of-synchronization condition for UMTS where it may be difficult to distinguish an out-of-synchronization condition in a downlink dedicated channel from interference in that channel.
2. Discussion of Related Art
Currently in the development of the Universal Mobile Telecommunications System (UMTS), there is no procedure defined on how the user equipment (UE) is supposed to handle an out-of-synchronization condition when it occurs. The synchronization model for UMTS is shown in the 3GPP Technical specification TS 25.401v1.0.0 (1999-04) xe2x80x9cUTRAN Overall Descriptionxe2x80x9d, at pp. 19-27. Further details can be found in the 3GPP Technical Specification TS 25.402v3.0.0 (2000-01) xe2x80x9cSynchronization in UTRAN Stage 2xe2x80x9d, and in other documents cross-referenced therein.
A generic solution that has been applied, for example, in IS-95, could be considered, based on the cyclic redundancy code (CRC) check results. With the IS-95 solution, time division duplex (TDD) specific issues are not taken into account, and the DTX (battery saving feature on a cellular phone that cuts back the output power when the speaker stops speaking) structure with UTRAN (UMTS Terrestrial Radio Access Network) TDD does not provide the CRC check in every frame, as in IS-95.
There is therefore a need to define how to handle an out-of-synchronization condition for UMTS.
It is an object of the present invention to define how to handle an out-of-synchronization condition for UMTS.
According to a first aspect of the invention, a method for use by user equipment in a mobile telecommunications system comprises the steps of sending a request on an uplink from a UE to a base station transceiver for increased power on a downlink channel experiencing a possible frames out-of-synchronization condition which may instead be a possible interference condition so as to attempt to eliminate said possible interference condition by increased power, and terminating said uplink after a first selected period of time without eliminating said possible interference problem unless a broadcast downlink channel is determined to be experiencing interference below a selected level in which case said UE continues to send said requests for increased power until after a second selected period of time without eliminating said possible interference problem after which said uplink is terminated.
According to a second aspect of the invention, a method for use by user equipment in a mobile telecommunications system comprises the steps of sensing in each UE a parameter having a magnitude indicative of a possible out-of-synchronization condition of each frame of a radio downlink channel from a base station transceiver to the UE, for providing a sensed signal have a magnitude indicative thereof, comparing said sensed signal to a threshold for providing a possible frame out-of-sync signal for each frame for which said sensed signal exceeds said threshold, signaling on a radio uplink from the mobile station to the BST, in response to said frame out-of-sync signal, a signal request for increased power on said radio downlink, incrementing, in response to each frame out-of-sync signal, a counter of possible frame out-of-sync signals, for providing a count signal indicative of a number of frames possibly out-of-synchronization, and comparing said count signal to a count threshold for providing an uplink shutdown signal in the presence of said count signal equalling or exceeding said count threshold.
Further according to the second aspect of the invention, the method further comprises the steps of delaying said providing said uplink shutdown signal in the presence of a downlink broadcast channel that is functioning with interference at an acceptable level and continuing said signaling on said radio uplink from the UE to the BST for increased power on said radio downlink, said incrementing said counter, and said comparing said count signal but now to a selected increased count threshold for providing said uplink shutdown signal in the presence of said count signal equalling or exceeding said selected increased count threshold.
According to a third aspect of the invention, a method for use in a mobile telecommunications system having plural cells, each cell having a base station transceiver for communicating over multiple radio links at the same time with corresponding multiple mobile stations in the cell and over additional radio links with corresponding additional UEs nearby but in other cells, comprises the steps of sensing in each UE a parameter having a magnitude indicative of a possible out-of-synchronization condition of each frame of a radio downlink channel from the BST to the UE, for providing a sensed signal having a magnitude indicative thereof, comparing said sensed signal to a threshold, for providing a possible frame out-of-sync signal for each frame for which said sensed signal exceeds said threshold, determining if a downlink broadcast channel is functioning properly for providing a broadcast channel health signal, providing an uplink shutdown signal to said BTS from said UE in the absence of said BCCH health signal and otherwise, signaling on a radio uplink from the UE to the BST, in response to both said BCCH health signal and said frame out-of-sync signal, a signal request for increased power on said radio downlink, incrementing in response to each frame out-of-sync signal, a counter of possible frame out-of-sync signals, for providing a count signal indicative of a number of frames possibly out-of-synchronization, and comparing said count signal to a count threshold for providing said uplink shutdown signal in the presence of said count signal equalling or exceeding said count threshold regardless of the presence or absence of said BCCH health signal.
According to a fourth aspect of the invention, user equipment for use in a mobile telecommunications system comprises means for sending a request on an uplink from said UE to a base station transceiver for increased power on a downlink channel experiencing a possible frames out-of-synchronization condition which may instead be a possible interference condition so as to attempt to eliminate said possible interference condition by increased power, and means for terminating said uplink after a first selected period of time without eliminating said possible interference problem unless a broadcast downlink channel is determined to be experiencing interference below a selected level in which case said UE continues to send said requests for increased power until after a second selected period of time without eliminating said possible interference problem after which said uplink is terminated.
According to a fifth aspect of the invention, user equipment for use in a mobile telecommunications system comprises means for sensing in each UE a parameter having a magnitude indicative of a possible out-of-synchronization condition of each frame of a radio downlink channel from a base station transceiver to the UE, for providing a sensed signal have a magnitude indicative thereof, means for comparing said sensed signal to a threshold for providing a possible frame out-of-sync signal for each frame for which said sensed signal exceeds said threshold, means for signaling on a radio uplink from the UE to the BST, in response to said frame out-of-sync signal, a signal (TPC) request for increased power on said radio downlink, means for providing, in response to each possible frame out-of-sync signal, a count signal indicative of a number of frames possibly out-of-synchronization, and means for comparing said count signal to a count threshold for providing an uplink shutdown signal in the presence of said count signal equaling or exceeding said count threshold.
In further accord with the fifth aspect of the invention, the user equipment further comprises means for delaying said providing said uplink shutdown signal in the presence of a downlink broadcast channel that is functioning with interference at an acceptable level whereby said signaling on said radio uplink from the UE to the BST for increased power on said radio downlink is continued for a selected period.
According to a sixth aspect of the invention, an apparatus for use in a mobile telecommunications system having plural cells, each cell having a base station transceiver for communicating over multiple radio links at the same time with corresponding multiple mobile stations in the cell and over additional radio links with corresponding additional UEs nearby but in other cells, comprises means for sensing in each UE a parameter having a magnitude indicative of a possible out-of-synchronization condition of each frame of a radio downlink channel from the BST to the UE, for providing a sensed signal having a magnitude indicative thereof, means for comparing said sensed signal to a threshold, for providing a possible frame out-of-sync signal for each frame for which said sensed signal exceeds said threshold, means for determining if a downlink broadcast channel is functioning properly for providing a broadcast channel health signal, means for providing an uplink shutdown signal to said BTS from said UE in the absence of said BCCH health signal, means for signaling on a radio uplink from the UE to the BST, in response to both said BCCH health signal and said frame out-of-sync signal, a signal request for increased power on said radio downlink, means for incrementing in response to each frame out-of-sync signal, a counter of possible frame out-of-sync signals, for providing a count signal indicative of a number of frames possibly out-of-synchronization, and means for comparing said count signal to a count threshold for providing said uplink shutdown signal in the presence of said count signal equaling or exceeding said count threshold regardless of the presence or absence of said BCCH health signal.
These and other objects, features and advantages of the present invention will become more apparent in light of the detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawing.